Apparatuses, computer program products, and methods for authenticating digital signals are provided in which copies of a watermark are extracted from a digital signal with at least some of the copies potentially having distorted values. The original values of the watermark may be reconstructed exclusively based on the extracted copies of the watermark. The method includes estimating one or more bit error rates without training or reference information. The bit error rates are modeled as being equivalent to transmitting the copies through binary symmetric channels. The estimated bit error rates and the distorted values are combined to reconstruct the original values of the watermark. The reconstructed watermark may be compared to an original watermark for authenticating the received digital signal. Also, the estimated bit error rates may be compared to a random sequence of bits for verifying the presence of the watermark without knowing the original values of the watermark.